Gallium nitride (GaN) is a prospect candidate for next-generation high-speed and high-power switching devices, due to its wide bandgap, high electron mobility and large breakdown voltage. Such kind of nitride can be grown on a silicon (Si) wafer by epitaxial growth, to be a so-called nitride-on-Si epitaxial wafer or epi-wafer.
The growth of GaN on a Si wafer is very difficult due to the large mismatch in lattice constants and thermal expansion coefficients, causing many drawbacks like warpage, slip lines, and cracks on the epitaxial wafer. Therefore, it is in need of a new and advanced solution of epitaxial wafer.